Cat Identity

Hi all. My brother has just purchased a house and it seems to have come with a cat. During the 3 house inspections this cat was here. And ever since Thursday it has just sat at the back door meowing. It is very friendly. And as soon as the back door is open he/she comes straight inside.

I was wondering if you guys could help me with what type of cat it is. As the previous house owners have moved over seas and the cat has no collar or tags on it.